Highly active, stable, and recyclable magnetic nano-size solid acid catalysts: efficient esterification of free fatty acid in grease to produce biodiesel
Highly active, stable, and recyclable magnetic nano-size solid acid catalysts: efficient esterification of free fatty acid in grease to produce biodiesel
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DOI：
10.1039/c2gc35779h
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发表时间：
2012-10
期刊：
影响因子：
9.8
通讯作者：
Zillillah;G. Tan;Zhi Li
中科院分区：
文献类型：
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作者：
Zillillah;G. Tan;Zhi Li
首次将磁性纳米固体酸催化剂用于游离脂肪酸（FFA）的酯化反应，以开发一种绿色高效的含FFA废弃油脂制备生物柴油（脂肪酸甲酯，FAME）的预处理工艺。PGMA-cat 4，由氧化铁磁性纳米颗粒（MNP）的核心、聚（甲基丙烯酸缩水甘油酯）（PGMA）壳和表面上的磺酸基团，通过用Na 2SO 3温和磺化由相应的含有环氧表面基团的核-壳结构的PGMA-MNP以98%产率合成，具有90 nm的平均尺寸，2.3 mmol H+ g-1的高酸容量，和优异的超顺磁性。使用该催化剂（4wt%）将油脂中的FFA（16wt%）与甲醇酯化，在2小时内得到96%的FFA转化为FAME。PGMA-cat 4在磁场下容易分离，并且在10个循环期间没有显示生产率损失。相比之下，PS-cat 12，由铁氧化物MNP的核，聚苯乙烯壳，和表面上的苯磺酸组成，是活性的，但不具有可回收性; Si-cat 14，由铁氧化物MNP的核，二氧化硅壳，和作为表面基团的磺酸组成，显示出较低的活性和差的回收性能。PGMA-cat 4的催化性能也优于微米级催化剂PGMA-cat（m）15和大尺寸固体酸催化剂Amberlyst 15。因此，本研究成功开发了一种新型、活性、稳定、可循环利用的磁性纳米固体酸催化剂，用于油脂中游离脂肪酸的绿色高效酯化反应，并将其作为废弃油脂制备生物柴油的预处理步骤。
Magnetic nano-size solid acid catalysts were prepared, characterized, and examined, for the first time, for the esterification of free fatty acid (FFA) to develop a green and efficient pretreatment step for producing biodiesel (fatty acid methyl ester, FAME) from waste grease containing FFA. PGMA-cat 4, consisting of a core of iron oxide magnetic nanoparticles (MNPs), a poly(glycidyl methacrylate) (PGMA) shell, and sulfonic acid groups on the surface, was synthesized in 98% yield from the corresponding core–shell structured PGMA–MNPs containing epoxy surface groups by gentle sulfonation with Na2SO3, possessing a mean size of 90 nm, high acid capacity of 2.3 mmol H+ g−1, and excellent superparamagnetic properties. Esterification of FFA (16 wt%) in grease with methanol using this catalyst (4 wt%) gave 96% conversion of FFA to FAME within 2 h. PGMA-cat 4 was easily separated under a magnetic field and showed no loss of productivity during 10 cycles. In comparison, PS-cat 12, consisting of a core of iron oxide MNPs, a polystyrene shell, and benzenesulfonic acids on the surface, was active but possessed no recyclability; Si-cat 14, consisting of a core of iron oxide MNPs, a silica shell, and sulfonic acids as surface groups, showed lower activity and poor recycling performance. The catalytic performance of PGMA-cat 4 was also better than those of the micro-size counterpart such as PGMA-cat (m) 15 and large-size solid acid catalysts such as Amberlyst 15. Thus, a novel, active, stable, and recyclable magnetic nano-size solid acid catalyst was successfully developed for the green and efficient esterification of FFA in grease as a pretreatment step to produce biodiesel from waste grease.